Detection of Active Microbial Enzymes in Nascent Sea Spray Aerosol: Implications for Atmospheric Chemistry and Climate

Abstract

The oceans cover nearly three-quarters of the Earth's surface and produce vast quantities of sea spray aerosols (SSA). Studies have shown that due to ocean biology SSA particles are comprised of much more than just sea salt and often include proteins, lipids, sugars, viruses, and bacteria. In this study, we show for the first time that a diverse array of microbial enzymes (protease, lipases, and alkaline phosphatase) are transferred from the ocean into the atmosphere and often become even more active with measured activities in SSA particles that are 1−2 orders of magnitude higher than those in bulk seawater. We hypothesize that these enzymatic reactions are enhanced in the interfacial environment of droplets and aerosols that can dynamically modify surface chemical species and properties. Simulations reveal that enzyme-containing SSA particles can rapidly coagulate with other preexisting aerosols, thus transferring the impact of enzyme reactions to a broad range of marine aerosols. These biotic reaction pathways are expected to profoundly change the composition of marine aerosols, particularly at the interface, and thus will impact cloud properties in marine environments. Future studies are needed to determine how photochemistry, changing ocean conditions in a warming climate, and other external factors will influence the activities of these enzymes and their impact on the composition of the marine atmosphere.

Concerted measurements of free amino acids at the Cabo Verde islands: high enrichments in submicron sea spray aerosol particles and cloud droplets

“…In the submicron size range, FAA contributed up to 5.3 % (average 1.1 %) to WSOC, while in the supermicron range, FAA only contributed up to 0.04 % to WSOC. Looking at FAA's total contribution to WSOC (PM 10 ), 0.7 % of WSOC consists of FAA, which is in good agreement with the value of the study by Mandalakis et al (2011). Considering the nitrogen content of the amino acids, FAA contributed to the estimated WSON (WSON = 25 % of measured TDN concentrations according to Lesworth et al, 2010) an average of 0.4 % in the submicron and of 0.05 % in the supermicron size ranges.…”

“…GABA is a metabolic product of the microbiological decarboxylation of Glu, which has been detected in all marine compartments. Active microbial enzymes on nascent sea spray aerosol have recently been reported by Malfatti et al (2019). The abundance of GABA in the submicron aerosol particles suggests that either GABA could have been produced by the microbiological decarboxylation of Glu by present (marine) microorganisms in the aerosol particles or that GABA was transferred from the seawater to the atmosphere.…”

“…Amino acids contribute to the global nitrogen and carbon cycle and to the atmosphere-biosphere nutrient cycle (Zhang and Anastasio, 2003;Wedyan and Preston, 2008). They can be divided into free single amino acids (FAAs) and combined amino acids (CAAs), which include proteins, peptides and other combined forms (Mandalakis et al, 2011). Amino acids are produced in the ocean and are reported to be in the upper layer of the ocean, the sea surface microlayer (SML) (Kuznetsova et al, 2004;Reinthaler et al, 2008;van Pinxteren et al, 2012;Engel and Galgani, 2016).…”

“…From the ocean, amino acids, as part of the class of proteinaceous compounds, can be transferred into atmospheric particles via bubble bursting (Kuznetsova et al, 2005;Rastelli et al, 2017). These proteinaceous compounds are often analyzed as sum parameter "proteins" using an analytical staining method with Coomassie blue developed by Bradford (1976) and have often been applied in previous studies (Gutiérrez-Castillo et al, 2005;Mandalakis et al, 2011;Rastelli et al, 2017). Despite their attribution to proteins, the FAAs are better utilizable forms of nitrogen instead of proteins for aquatic organisms such as phytoplankton and bacteria (Antia et al, 1991;McGregor and Anastasio, 2001).…”

Satellite‐based top‐down Lagrangian approach to quantify aerosol emissions over California

“…These short‐lived particles, though present in small mass fraction, influence the weather and climate by altering the atmospheric radiation and the spatial distribution of latent heat. Atmospheric aerosols not only influence the radiation budget (Schwartz, ; Ramanathan et al ., ; Guleria and Kuniyal, ; ) but also impact cloud formation (Twomey, ; Steinfeld, ; Li et al ., ), atmospheric chemistry (Andreae, ; Malfatti et al ., ; Zhu et al ., ), human health (Hoek et al ., ; Pope et al ., ; Fuzzi et al ., ), and agriculture (Ainsworth and Long, ). Aerosols are emitted into the Earth's atmosphere from various natural and anthropogenic sources.…”